Justinussen J L, Holm A, Kornum B R
Molecular Sleep Lab, Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark.
Molecular Sleep Lab, Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark; Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, Rigshospitalet, Glostrup, Denmark.
Neuroscience. 2015 Dec 3;310:354-61. doi: 10.1016/j.neuroscience.2015.09.050. Epub 2015 Sep 28.
The hypocretin/orexin system regulates, among other things, sleep and energy homeostasis. The system is likely regulated by both homeostatic and circadian mechanisms. Little is known about local differences in the regulation of hypocretin activity. The aim of this study was to establish an optimized peptide quantification method for hypocretin-1 extracted from different mouse brain areas and use this method for investigating circadian fluctuations of hypocretin-1 levels in these areas. The results show that hypocretin-1 peptide can be extracted from small pieces of intact tissue, with sufficient yield for measurements in a standard radioimmunoassay. Utilizing the optimized method, it was found that prepro-hypocretin mRNA and peptide show circadian fluctuations in the mouse brain. This study further demonstrates that the hypocretin-1 peptide level in the frontal brain peaks during dark as does prepro-hypocretin mRNA in the hypothalamus. However, in midbrain and brainstem tissue caudal to the hypothalamus, there was less circadian fluctuation and a tendency for higher levels during the light phase. These data suggest that regulation of the hypocretin system differs between brain areas.
下丘脑泌素/食欲素系统除其他功能外，还调节睡眠和能量平衡。该系统可能受稳态机制和昼夜节律机制的共同调节。关于下丘脑泌素活性调节的局部差异，人们了解甚少。本研究的目的是建立一种优化的肽定量方法，用于从不同小鼠脑区提取的下丘脑泌素-1，并使用该方法研究这些脑区中下丘脑泌素-1水平的昼夜波动。结果表明，下丘脑泌素-1肽可以从小片完整组织中提取，其产量足以用于标准放射免疫测定。利用优化后的方法，发现前体下丘脑泌素mRNA和肽在小鼠脑中呈现昼夜波动。本研究进一步证明，额叶脑区的下丘脑泌素-1肽水平在黑暗期达到峰值，而下丘脑的前体下丘脑泌素mRNA也是如此。然而，在下丘脑尾侧的中脑和脑干组织中，昼夜波动较小，且在光照期有水平较高的趋势。这些数据表明，下丘脑泌素系统的调节在不同脑区存在差异。
